Soft body armor durability entails many parameters and can be broadly described as the armor system's ability to withstand or resist wear from axial, torsional and bending motions, as well laundering, temperature and humidity exposure, POL and salt water exposure and non-penetrating blunt impact resistance.
The question of how long soft body armor will last is a frequent question of Army logisticians and law enforcement officials. Unfortunately, no definitive answer can be given to this question regarding service life, which encompasses many variables such as wear (including bending, twisting, and folding), care (including launderability, handling, and storage), and temperature/humidity exposure, etc. Every piece of body armor has a service life and will eventually have to be replaced.
Currently, the only method to quantitatively evaluate body armor performance is destructive ballistic testing. Age alone does not cause the body armor's ballistic resistance to deteriorate (shelf life). The care and maintenance of a garment (or the lack thereof) have been shown to have a greater impact to service life of body armor than shelf life. As of today there is no way to determine the service life of soft body armor. Having the ability to do so could reduce life-cycle costs associated with sustainment and re-issuance. More importantly, it could be used to determine if a soft body armor design can maintain its ballistic integrity for some expected level of use/time. Therefore, the need exists to identify relevant variables and meaningful methods of measuring the approximate service life of body armor systems based on actual wear and care (not just on shelf life alone).
Current test methods for abrasion resistance and durability of textile-based and film systems include ASTM (American Society for Testing and Materials) test methods. These methods typically involve mechanical oscillations to cause abrasion damage to a fabric sample. Generally, the approaches use a series of rollers and bars to apply stresses onto the test material. However, even methods that provide more complex motion mainly focus on testing one layer of fabric at a time, and not a system-level test of a full body armor system. Additionally, these types of testing systems only impart abrasion on the test material and do not focus on durability of the test material in an end user situation. It would be advantageous to accommodate a full body armor system in a durability test.
U.S. Pat. No. 8,225,638 (Honeywell) describes a system for testing the durability and wear resistance of soft armor. Honeywell relies on a reciprocating drive that forces the textile system back and forth along its length. The flexible fabrics are turned as it passes through the rollers. However, the use of rollers may not approximate the forces and stresses experienced in the use of ballistic resistant fabric and composite articles. These can include forces and stresses resulting from actions such as squatting (compression), bending (flexion/extension) and twisting (torsion). It would be advantageous to have a test apparatus capable of subjecting a multi-layered soft armor system to each of the forces and stresses that are typically experienced as a result of basic human motion that would be experienced during end-item use.
Accordingly, it would be desirable to provide a soft body armor durability test system and method that addresses at least some of the problems identified above.